Current industry trends have increased demand for magnetic recording devices which have the ability to record data with high in-plane recording density along with a reduction in size of each magnetic fine-particle of a magnetic recording medium. In addition, a reduction in the size of the writing pole has been demanded in order to increase the amount of recording information which can be put into magnetic recording mediums. However, reduction in the size of each magnetic fine-particle results in a decrease in the total volume of the magnetic fine-particles; consequently, a thermal fluctuation of magnetization has been problematically caused as a factor of destabilization in a magnetization area of the magnetic recording medium. As a method for solving the problem, a perpendicular magnetic recording method has been proposed, in which a magnetization signal is recorded in a direction perpendicular to a recording medium while increasing the volume of the magnetic fine-particles by increasing a thickness of a recording layer. A main pole of a magnetic recording head used in perpendicular magnetic recording has an inverted trapezoidal profile that is large in width on a trailing side, and small in width on a leading side with respect to a running direction of the magnetic recording medium, so that a difference is given between an amount of magnetic flux emitted from the trailing side of the main pole and an amount of magnetic flux emitted from the leading side thereof due to a Bevel angle (slope angle formed by two different widths, width on a trailing side of a throat height of the main pole and width on a leading side thereof), Thereby, the main pole has a magnetic clearance angle for preventing attenuation and erasing of information data on an adjacent track when information is written into a magnetic recording medium. Even in the perpendicular magnetic recording method, a single pole portion for writing, which generates a perpendicular recording magnetic-field to a magnetic recording medium, is currently reduced in width to increase surface recording density. Consequently, it is now increasingly difficult to generate an adequate perpendicular magnetic field for reversal of magnetization of a magnetic recording medium.
Current industry trends have increased demand for magnetic recording devices which have the ability to record data with high in-plane recording density along with a reduction in size of each magnetic fine-particle of a magnetic recording medium. In addition, a reduction in the size of the writing pole has been demanded in order to increase the amount of recording information which can be put into magnetic recording mediums. However, reduction in the size of each magnetic fine-particle results in a decrease in the total volume of the magnetic fine-particles; consequently, a thennal fluctuation of magnetization has been problematically caused as a factor of destabilization in a magnetization area of the magnetic recording medium. As a method for solving the problem, a perpendicular magnetic recording method has been proposed, in which a magnetization signal is recorded in a direction perpendicular to a recording medium while increasing the volume of the magnetic fine-particles by increasing a thickness of a recording layer. A main pole of a magnetic recording head used in perpendicular magnetic recording has an inverted trapezoidal profile that is large in width on a trailing side, and small in width on a leading side with respect to a running direction of the magnetic recording medium, so that a difference is given between an amount of magnetic flux emitted from the trailing side of the main pole and an amount of magnetic flux emitted from the leading side thereof due to a bevel angle (slope angle formed by two different widths, width on a trailing side of a throat height of the main pole and width on a leading side thereof), Thereby, the main pole has a magnetic clearance angle for preventing attenuation and erasing of information data on an adjacent track when information is written into a magnetic recording medium. Even in the perpendicular magnetic recording method, a. single pole portion for writing, which generates a perpendicular recording magnetic-field to a magnetic recording medium, is currently reduced in width to increase surface recording density. Consequently, it is now increasingly difficult to generate an adequate perpendicular magnetic field for reversal of magnetization of a magnetic recording medium.
Furthermore, when a suspension arm fixed with a slider mounted with a magnetic head is scanned from an inner side to an outer side of a magnetic recording medium for recording and reproducing, an angle of the magnetic head varies depending on a position of a recording/reproducing track of the magnetic recording medium. Such an angle is a so-called skew angle. When a magnetic head has a skew angle, since the main pole of the recording head also has the same angle, data on an adjacent track are attenuated and erased regardless of which track of the magnetic recording medium the magnetic head is positioned on. Therefore, it is essential for achieving high recording density that a high magnetic field is emitted to a recording layer of a magnetic recording medium while securing a certain magnetic clearance angle.
Thus, a method is given to obtain an adequate magnetic clearance angle, where thickness of a main pole is reduced, or a bevel angle of the main pole is increased. However, this reduces a magnetic-flux emitting area of an ABS of the main pole, leading to a reduction in magnetic field strength.
As a measure for this, a method is described in each of Japanese Patent Office (JPO) Pub. Nos. JP-A-2007-220208, JP-A-2007-220209 and JP-A-2007-242132, in which a main pole profile is formed into a T-shape. Thereby, a certain magnetic field strength is secured while a geometric width of a writing track is defined by a wide region, so that a certain magnetic clearance angle is secured on a magnetic recording medium side.
To achieve high in-plane recording density, in one approach, a size of each magnetic particle of a magnetic recording medium is reduced. In addition, a width of a recording/reproducing track of a magnetic head can be reduced. Reduction in a width of a single pole for writing of a recording head causes a decrease in an area of a main pole in an ABS, leading to a reduction in a writing field strength being proportional to a magnetic-pole area. Moreover, a certain magnetic clearance angle is secured to prevent attenuation and erasing of information written into an adjacent track even if a magnetic head has a skew angle.
FIG. 23 is a conceptual view showing a position of a magnetic recording head with respect to a magnetic recording medium. FIG. 23 shows a structure where a slider is fixed to a suspension arm and is moved in an outer circumferential direction of a magnetic recording head 11, and the head has a skew angle. When the main pole is a rectangular main-pole 1a on a track C, which has no bevel angle, distribution of a magnetic field strength for reversal of magnetization in a recording layer of the magnetic recording medium spreads along each side face of a writing pole, and is decreased in width with an increase in distance from a leading side of the main pole. Therefore, a writing magnetic field on the leading side is applied to part of an adjacent track B, leading to attenuation and erasing of information written into the track B.
However, in the case of a main-pole 1a on a track A, which has a bevel angle and thus has an inverted trapezoidal profile, while distribution of a magnetic field strength spreads along a writing pole, since the bevel angle allows formation of a magnetic clearance angle (angle of a contour line, of which the recording field strength of a main pole corresponds to a coercive force of a recording medium, in a leading side direction from a widest point in a track direction on the contour line) with respect to an adjacent track, information can be recorded without affecting the adjacent track. From this, it is known that the bevel angle of the main pole has a great role in performance of the head. However, since track width is reduced with an increase in a recording density, the bevel angle is problematically hardly formed. Moreover, an area of a main pole in an ABS is reduced due to a reduction in width of the main pole, leading to a problem of a reduction in writing field strength.
Therefore, it would be beneficial to have a magnetic head which could overcome these problems associated with current head designs.